JP2014238547A - Pressure roll, fixing apparatus, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure roll configured to improve heat resistance, while maintaining durability.SOLUTION: In a pressure roll 91, a heat-resistant elastic layer 912 includes a plurality of oblate holes 914 each having a major axis oriented in a radial direction of the elastic layer 912. The oblate hole in the elastic layer selects a minor axis and a major axis of the oblate hole according to compressibility of the pressed elastic layer. A ratio B/A between a major axis A and a minor axis B of the oblate hole is 0.7-0.9.

Description

  The present invention relates to a pressure roll, a fixing device, and an image forming apparatus.

  Conventionally, in an image forming apparatus such as an electrophotographic copying machine or printer, a process for fixing an unfixed toner image held on a recording medium such as paper on the recording medium to form an image is called a fixing process. It is out. Conventionally, methods such as pressure fixing, oven fixing, and solvent fixing are used as the fixing step, but heat is effectively transmitted, the toner image is fixed more firmly, and is relatively safe. From the viewpoint, the thermal pressure fixing method is most commonly used. In this thermal pressure fixing method, a recording medium on which an unfixed toner image is held is passed through a nip constituted by two heated rolls or belts, and when the nip passes, the recording medium is heated by the rolls or belts to be in a molten state. This is a method in which a toner image is fixed on a recording medium by pressing the unfixed toner image that has been pressed against the recording medium by nip pressure.

  Here, in Patent Document 1, in the elastic roller used for fixing, a plurality of holes are formed in the elastic layer of the elastic roller, and the plurality of holes extend in the axial direction of the elastic layer and have a radius. A plurality of strut walls that are inclined with respect to the line are formed at equal intervals in the circumferential direction, and further, an arbitrary radial line of the elastic roller is formed so as to always pass through one of the holes. Therefore, it is described that when the elastic roller comes into contact with the counterpart, the holes in the contact range are almost completely crushed by the contact pressure, and a high contact pressure is obtained.

  In Patent Document 2, a heating member is introduced into a nip portion where a heating unit and a pressure roller are in contact with each other, nipped and conveyed, and in a heating apparatus that heats the member to be heated, the thermal conductivity of the pressure roller is set. In order to make it low, it is disclosed that the elastic layer of the pressure roller contains a dispersed space formed by heating and expanding a resin microballoon.

  In Patent Document 3, in an image heating apparatus that transports a recording material to a nip where a heating unit and a pressure roller are in contact with each other and heats an image on the recording material, the elastic layer of the pressure roller includes “water-containing”. It is made of a foam obtained by thermosetting a rubber composition in which a water-absorbing polymer and a hollow filler are dispersed, and an average diameter formed by evaporation of water from the water-absorbing polymer during thermosetting. It is disclosed to have foam cells in the range of 10 μm to 500 μm.

JP-A-62-258216 JP 2002-148988 A JP 2009-134310 A

  An object of the present invention is to provide a pressure roll, a fixing device, and an image forming apparatus that have higher heat insulation properties while ensuring strength than in the past.

  As a result of intensive studies to solve the above problems, the present invention has been reached as follows.

  (1) At least an elastic layer and a release layer are provided on the core material, and the elastic layer has a plurality of three-dimensional holes different from at least one of the three diameters, and the long diameter of the holes Is a pressure roll oriented in the radial direction of the elastic layer.

  (2) The holes in the elastic layer are oblate, and the short diameter and the long diameter of the oblong holes are selected according to the compressibility of the elastic layer during pressurization. It is a pressure roll of description.

  (3) B / A, which is the ratio of the major axis A to the minor axis B of the oblong hole, is 0.7 or more and 0.9 or less, as described in (2) above It is a pressure roll.

  (4) Unfixed toner in a nip portion formed between the pressure roll according to any one of (1) to (3) above and the pressure roll, and formed between the pressure roll And a fixing member that fixes the unfixed toner image on the recording medium by sandwiching the recording medium carrying the image.

  (5) The fixing device according to (4), wherein the fixing member is a fixing roller or a belt member provided rotatably.

  (6) A latent image forming means for forming a latent image on the image carrier, a developing means for developing the latent image using a developer for developing an electrostatic image, and the developed toner image via an intermediate transfer member. The image forming apparatus includes: a transfer unit that transfers the toner image on the transfer body; and a fixing unit that fixes the toner image on the transfer body. An image forming apparatus comprising the fixing device according to 5).

  According to the invention described in claim 1 of the present application, compared to the case where the present configuration is not provided, the heat insulating property is enhanced while ensuring the strength.

  According to the invention described in claim 2 of the present application, compared to the case where the present configuration is not provided, the heat insulating property is enhanced while ensuring higher strength.

  According to the invention described in claim 3 of the present application, compared with the case where the present configuration is not provided, the heat insulating property is enhanced while ensuring the strength within a range suitable for practical use.

  According to the invention described in claim 4 of the present application, it is possible to obtain a fixing device including a pressure roll having high heat insulation while ensuring strength as compared with the case where the present configuration is not provided.

  According to the invention described in claim 5 of the present application, it is possible to obtain a fixing device including a pressure roll having high heat insulation while ensuring strength as compared with the case where the present configuration is not provided.

  According to the invention described in claim 6 of the present application, an image forming apparatus having a fixing device having a pressure roll having high heat insulation while ensuring strength can be obtained as compared with the case without this configuration.

It is a schematic block diagram which shows an example of a structure of the pressure roll fixing device in this invention. It is sectional drawing along the II line of FIG. 1 explaining an example of a pressure roll. It is explanatory drawing of a pressure roll. 1 is a schematic configuration diagram illustrating an example of a fixing device according to the present invention. 1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to the present invention.

  A pressure roll, a fixing device, and an image forming apparatus according to an embodiment of the present invention will be described below.

[Fixing device]
First, the fixing device in the present embodiment will be described below with reference to FIG. Note that a fixing device that presses the fixing belt using a heat source as a heating unit will be described as an example of the fixing device of the present embodiment.

  As shown in FIG. 4, the fixing device 90 of the present embodiment is disposed in pressure contact with a pressure roll 91 that is a rotatable rotating member and a pressure roll 91 that is a rotating member. An unfixed toner image is fixed to the recording medium P by sandwiching a sheet P, which is a recording medium holding an unfixed toner image, in a pressure part N (hereinafter also referred to as “nip part N”) formed in And a fixing belt 92 that is a rotatable tubular body.

  Here, a ceramic heater 82 which is a resistance heating element as an example of a heat generation source is disposed inside the fixing belt 92, and heat is supplied from the ceramic heater 82 to the nip portion N. The ceramic heater 82 has a substantially flat surface on the pressure roll 91 side. Then, it is arranged in a state of being pressed against the pressure roll 91 via the fixing belt 92 and forms a nip portion N. Therefore, the ceramic heater 82 also functions as a pressure member. The paper P that has passed through the pressure unit N is peeled off from the fixing belt 92 due to a change in the curvature of the fixing belt 92 in the exit region (peeling nip portion) of the pressure unit N.

  Further, in order to reduce the sliding resistance between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82 between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82, a sliding sheet 68 as an example of a rubbing member. Is arranged. The sliding sheet 68 may be configured separately from the ceramic heater 82 or may be configured integrally with the ceramic heater 82.

  On the other hand, a pressure roll 91 as an example of a rotating member is disposed so as to face the fixing belt 92 and is rotated in the direction of arrow D by a driving motor (not shown). It follows and rotates in the direction of arrow E. The pressure roll 91 is configured by laminating a core (cylindrical cored bar) 911, an elastic layer 912 coated on the outer peripheral surface of the core 911, and a release layer 913 made of a heat resistant resin coating or a heat resistant rubber coating. Has been.

  The fixing belt 92 is an endless belt whose original shape is formed in a cylindrical shape. For example, a base layer 921 made of a thermosetting polyimide resin, a thermoplastic polyimide resin, a polyamideimide resin, a polybenzimidazole resin, or the like, It is composed of a release layer 922 made of a fluororesin or the like, which is coated on the surface (outer peripheral surface) or both surfaces of the base layer 921 on the pressure roll 91 side.

  Here, the fixing belt 92 includes a ceramic heater 82 disposed inside the fixing belt 92, an upstream belt guide member 93 a and a downstream belt guide member 93 b, a holder 65 that holds the ceramic heater 82, and further the fixing belt 92. Are supported by an edge guide member (not shown) as an example of a belt regulating member disposed at both ends of the belt. In the fixing device 90 of the present embodiment, since the sliding sheet 68 is configured to cover only the ceramic heater 82, the upstream belt guide member 93 a and the downstream belt guide member 93 b are both included in the fixing belt 92. The fixing belt 92 is supported while directly rubbing against the peripheral surface.

  The holder 65 is provided with a lubricant application member 67 along the longitudinal direction of the fixing device 90. The lubricant applying member 67 contacts the inner peripheral surface of the fixing belt 92 and supplies the lubricant to the sliding portion between the fixing belt 92 and the sliding sheet 68. Examples of the lubricant include liquid oils such as silicone oil and fluorine oil; grease in which a solid substance and a liquid are mixed, and a combination thereof.

  Then, the sheet P on which the toner image is electrostatically transferred in the image forming apparatus is guided to the nip portion N of the fixing device 90 by the fixing inlet guide 56. When the paper P passes through the nip portion N, the toner image on the paper P is fixed by the pressure acting on the nip portion N and the heat supplied from the ceramic heater 82 on the fixing belt 92 side. Also in the fixing device 90 of the present embodiment, since the nip portion N can be configured widely between the pressure roll 91 and the ceramic heater 82, stable fixing performance can be ensured.

  As an auxiliary means for completely separating the fixed sheet P from the fixing belt 92, a peeling assisting member 70 can be disposed on the downstream side of the nip portion N of the fixing belt 92. The peeling auxiliary member 70 is held by a baffle holder 72 in a state where the peeling baffle 71 is close to the fixing belt 92 in a direction (counter direction) opposite to the rotation direction of the fixing belt 92.

  The pressure roll 91 includes, for example, a solid iron core (columnar metal core) 911 having a diameter of 16 mm, an elastic layer 912 such as a silicone sponge having a thickness of 12 mm, which covers the outer peripheral surface of the core 911, and the like. And a release layer 913 with a heat-resistant resin coating such as PFA having a thickness of 30 μm or a heat-resistant rubber coating. In addition, as a manufacturing method of the pressure roll 91, for example, a fluororesin tube in which an adhesion primer is applied to the inner peripheral surface of a PFA tube (becomes a release layer 913) and a solid shaft (becomes a core 911) Is set in the mold, and after injecting the liquid foamed silicone rubber between the fluororesin tube and the solid shaft, the silicone rubber is vulcanized and foamed by heat treatment (for example, 150 ° C, 2 hours) to make it elastic. A method of forming the layer 912 can be given. In addition, the structure of the pressure roll 91 of this Embodiment is later mentioned using FIG.

  The pressure roll 91 is disposed so as to face the fixing belt 92, rotates in the direction of arrow D at a process speed of, for example, 140 mm / sec, and drives the fixing belt 92. Further, the pressure belt 91 is held by the pressure roller 91 and the ceramic heater 82 to form the pressure portion N, and the recording medium P holding the unfixed toner image is passed through the pressure portion N. Then, heat and pressure are applied to fix the unfixed toner image on the recording medium P.

  In the fixing device 90, the fixing belt 92 is driven to rotate as the pressure roll 91 rotates in the direction of arrow D, and the outer peripheral surface of the fixing belt 92 is heated to a temperature at which fixing can be performed by heating by the ceramic heater 82. The fixing belt 92 heated in this way moves to the pressure part N with the pressure roll 91. The sheet P on which the unfixed toner image is provided is carried into the fixing device 90 via the fixing inlet guide 56 by the conveying means. When the paper P passes through the pressure part N of the fixing belt 92 and the pressure roll 91, the unfixed toner image is heated by the fixing belt 92 and fixed on the surface of the paper P. Thereafter, the sheet P on which the image is formed is transported by a transport unit and is discharged from the fixing device 90.

[Pressure roll]
Hereinafter, the pressure roll in the present embodiment will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, a pressure roll 91 according to the present embodiment includes a core (cylindrical cored bar) 911, an elastic layer 912 that covers the outer peripheral surface of the core 911, and a heat-resistant resin-coated or heat-resistant rubber. A release layer 913 formed by coating is laminated.

  In the pressure roll 91 according to the present embodiment, as shown in FIG. 2, the heat-resistant elastic layer 912 has a plurality of holes 914 in which at least one of the three diameters is different from the others, and the holes 914. The major axis is oriented in the radial direction of the elastic layer 912. In the pressure roll 91, the air holes 914 have an advantageous effect on heat insulation. However, since the elastic layer 912 has pores, the overall strength is somewhat sacrificed. Therefore, since the direction in which the pressure roll 91 compresses is the radial direction, in the present embodiment, when a force is applied by bringing the major axis of the air hole 914 along the radial direction (in other words, the compression rate) In this case, the strength of the elastic layer 912 is ensured. In addition, since the shape which can ensure the strongest is a true sphere, the hole 914 is preferably a flat sphere. Here, the “oblate ball” refers to a rotating body obtained when the ellipse is rotated about the minor axis of the ellipse. However, it is not necessary to make two of the three diameters of the rotating body exactly equal, and some errors are allowed. Of course, since it is ideal to approach the true sphere when compressed, it goes without saying that the two diameters are preferably equal.

  Furthermore, the oblong holes 914 in the elastic layer 912 of the pressure roll 91 according to the present embodiment have a short diameter B and a long diameter of the oblong holes 914 according to the compressibility of the elastic layer 912 at the time of pressurization. A is appropriately selected. Here, as shown in FIG. 3, the long diameter A of the oblong hole 914 corresponds to the “compression direction diameter” along the direction in which the pressure roll 91 is compressed (the direction of the white arrow in FIG. 3). The short diameter B of the oblong hole 914 in Formula 1 corresponds to the “non-compression direction diameter” with respect to the compression direction. Here, the “compression rate” is a state quantity that represents how much the thickness of the elastic layer in the radial direction changes with respect to the pressure applied in the radial direction of the pressure roll 91.

The compression rate of the pressure roll 91 is obtained based on Expression 1: Compression rate = {compression amount of the pressure roll 91 / thickness of the elastic layer 912 of the pressure roll 91} × 100. Here, in the present embodiment, when the fixing device includes the pressure roll 91 and the fixing belt 92 shown in FIG. 4, the compression amount of the pressure roll 91 is the rotation axis of the pressure roll 91 before and after fixing and the fixing belt. The difference between the inter-axis distance L ₀ between the virtual rotation axis 92 and the inter-axis distance L ₁ between the rotation axis of the pressure roll 91 and the virtual rotation axis of the fixing belt 92 when forming the nip portion N during fixing. . When the fixing device is composed of a pressure roll having an elastic layer and a fixing member having an elastic layer, the difference between the axial distances between before and after fixing and at the time of fixing is obtained by subtracting the fixing side component. The amount of compression.

  On the other hand, the relationship between the compression rate of the pressure roll 91 and the shape of the oblong holes is, for example, Expression 2: Compression rate (%) of the elastic layer 912 = {100− (B / A) × 100} ( In the formula, A: the long diameter of the oblong hole 914 and B: the short diameter of the oblong hole 914) are satisfied.

  Therefore, the elastic layer 912 of the pressure roll 91 is formed by appropriately selecting the long diameter A and the short diameter B of the oblong holes 914 in the expression 2 based on the “compression ratio” obtained in the expression 1. Is preferred.

  Further, in the elastic layer 912 of the pressure roll 91 in the present embodiment, the compression ratio of the elastic layer 912 at the time of pressing is 10% or more and 30% or less, and the major axis A and minor axis B of the oblong hole 914 are The ratio satisfies the relationship of 0.7 ≦ B / A ≦ 0.9. Here, when the B / A in the oblong hole 914 is less than 0.7, the elastic layer 912 is broken during compression, while when the B / A exceeds 0.9, the pressure roll The compression ratio of the elastic layer 912 of 91 is low, and a necessary amount of the nip portion N region may not be formed between the pressure roll 91 and the fixing belt 92.

  In the present embodiment, the short diameter B of the oblong hole 914 is preferably, for example, 10 μm or more and 130 μm or less, and the long diameter A of the oblong hole 914 is, for example, the short diameter B × 1. It is preferable that the diameter is 1 or more and B * 1.3 or less.

  The hardness of the elastic layer 912 of the pressure roll 91 in this embodiment is 50 ° or less, preferably 30 ° or more and 40 ° or less when measured using an Asker rubber hardness meter C type (manufactured by Kobunshi Keiki Co., Ltd.). It is. The elastic layer 912 has a tensile stress of 4 MPa or less, preferably 0.5 MPa or more and 4 MPa or less, according to JIS K-6251.

  In the present embodiment, the elastic layer 912 of the pressure roll 91 is formed by, for example, any one of the following three manufacturing methods so that the long diameter of the hole 914 is oriented in the radial direction of the elastic layer 912. Then, the pressure roll 91 is manufactured.

  First, in the first manufacturing method, a metal shaft adjusted to the core diameter of the core 911 is attached to a cylindrical mold, and the liquid silicone rubber (manufactured by Toray Dow Corning Co., Ltd.) has a diameter ratio of 10% or more in advance. Appropriate amount of a spherical filler that volatilizes by firing at the time of elastic layer formation or a spherical filler that volatilizes by firing at the time of elastic layer formation, for example, 30 parts by mass with respect to 100 parts by mass of liquid silicone rubber The blended elastic material is injected between the circular mold and the metal shaft. Next, the cylindrical mold into which the elastic material is injected is heated to a temperature near the curing temperature of the liquid silicone rubber, for example, 80 ° C. or more and 100 ° C. or less, and the oblate filler in the elastic material moves in the radial direction of the cylindrical mold. It is rotated at a speed that aligns or a speed that a spherical filler moves in an appropriate amount in the radial direction of the cylindrical mold, for example, a speed of 5 rpm to 50 rpm. At this time, an oven with a rotating device may be used. Next, the cured elastic cylindrical body made of silicone rubber is taken out from the cylindrical mold, and the hollow elastic cylindrical body is fired at a firing temperature (eg, about 200 ° C.) for a predetermined time (eg, about 2 hours). The filler in the elastic cylinder is volatilized. Next, the core 911 to which the primer is applied is attached to the hollow portion of the elastic cylinder, and then bonded and fired. Further, the primer is applied to the surface of the obtained elastic cylinder with the core, and another cylindrical mold A heat-resistant resin coating or a heat-resistant rubber coating serving as a release layer is covered inside, and the elastic cylinder is inserted in a vacuumed state, and then returned to normal pressure to form a pressure roll precursor. Then, the pressure roll precursor is taken out from the cylindrical mold, and an elastic layer made of an elastic cylinder and a release layer are bonded and fired in an oven to produce a pressure roll.

  In the second manufacturing method, instead of adjusting the rotational speed of the cylindrical mold of the first manufacturing method, an ultrasonic vibration device is attached to the outer periphery of the cylindrical mold into which the elastic material is injected, and the elastic material is injected. When the cylindrical mold is rotated while being heated near the curing temperature of the liquid silicone rubber, for example, 80 ° C. or more and 100 ° C. or less, ultrasonic vibration is applied to the elastic material in the cylindrical mold, The press roll is manufactured in accordance with the first manufacturing method except that the spherical filler is aligned in the radial direction of the cylindrical mold or the spherical filler is moved in an appropriate amount in the radial direction of the cylindrical mold. .

  Here, as a filler used in the first manufacturing method and the second manufacturing method, for example, a resin filler that softens at the curing temperature of the silicone rubber and volatilizes at the firing temperature of the elastic layer made of the cured silicone rubber. And resin balloons.

  Examples of the resin filler include polymer hydrocarbons that soften near the curing temperature of the silicone rubber, for example, 80 ° C. or more and 100 ° C. or less, and volatilize at the firing temperature at the time of forming the elastic layer, for example, 200 ° C. As such a polymer hydrocarbon, for example, polyethylene that softens at around 100 ° C. is suitable. When a resin filler made of polyethylene is used, a spherical filler whose diameter ratio is 10% or more and 30% or less in advance and volatilizes by firing at the time of forming an elastic layer may be volatilized by firing at the time of forming an elastic layer. It may be a spherical filler. For example, in the case of a spherical filler of polyethylene, the spherical filler is easily deformed at the softening temperature of polyethylene, and when a centrifugal force is applied in the radial direction or ultrasonic vibration is applied at this time, the spherical filler is flattened in the radial direction. An elastic cylindrical body in which the spherically deformed filler is oriented is obtained. By firing this elastic cylindrical body, finally, as shown in FIG. 2, the elastic layer 912 of the pressure roll 91 has a plurality of holes 914 in which at least one of the three diameters is different from the others, The long diameter of the air holes 914 is oriented in the radial direction of the elastic layer 912.

  Examples of the resin balloon include thermally expandable microcapsules. Examples of thermally expandable microcapsules include F series and FN series of “Matsumoto Microsphere (registered trademark)” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.). Is mentioned. The F series and FN series of “Matsumoto Microsphere (registered trademark)” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) are microcapsules in which liquid low-boiling hydrocarbons are wrapped in a thermoplastic polymer shell. Since the polymer shell is softened and the liquid hydrocarbon in the thermoplastic polymer shell is changed to a gas, the capsule is expanded by the pressure and the volume is increased. Here, as “Matsumoto Microsphere (registered trademark)” used in the present embodiment, for example, low-temperature expansion type “F-30”, “F-36” having a maximum expansion temperature of 110 ° C. or more and 135 ° C. or less. ”,“ F-36LV ”,“ F-48 ”,“ FN-80GS ”,“ F-50 ”, for example, medium-temperature expansion type“ F-65 ”,“ FN ”having a maximum expansion temperature of 145 ° C. or more and 165 ° C. or less. −100SS ”,“ FN-100S ”,“ F-100M ”, for example, high-temperature expansion type“ FN-100M ”,“ FN-100 ”,“ FN-105 ”having a maximum expansion temperature of 165 ° C. or more and 185 ° C. or less, “FN-180SS”, “FN-180S”, “FN-180”, for example, an ultra-high temperature expansion type “F-190D” having a foaming start temperature of 160 ° C. to 200 ° C. and a maximum expansion temperature of 210 ° C. to 260 ° C., "F-230 "It includes" F-260D ".

  Furthermore, as a resin balloon, the above-mentioned Matsumoto Microsphere (registered trademark) F series and FN series already expanded bodies (true specific gravity: 0.02 to 0.04) are sold as wet bodies of about 90% water content. For example, “F-30E”, “F-50E”, “F-65E”, and the above-mentioned “Matsumoto Micro” of the FE series (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) of “Matsumoto Microsphere (registered trademark)” Sphere (registered trademark) F series and FN series already expanded bodies (true specific gravity: 0.02 to 0.04) sold at a solid content of about 97% or more "Matsumoto Microsphere (registered trademark)" ) "F-DE series (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), for example," FN-80SDE "," F-65DE "," F-80DE ".

  A third manufacturing method is a resin filler including a conductive filler having an aspect ratio of 1.1 or more and 3.0 or less as a filler to be used instead of adjusting the rotational speed of the cylindrical mold of the first manufacturing method. A device for applying a magnetic field is attached to the outer periphery of the cylindrical mold into which the elastic material is injected, and the cylindrical mold into which the elastic material is injected is set near the curing temperature of the liquid silicone rubber, for example, 80 ° C. or more and 100 ° C. or less. When rotating while heating, pressurizing roll according to the first manufacturing method, except that a magnetic field is applied and the conductive filler contained in the softened resin filler is oriented in the radial direction of the cylindrical mold. Manufacturing.

[Image forming apparatus]
FIG. 5 shows a schematic configuration of an image forming apparatus to which the sliding sheet and the fixing device of the present embodiment are applied. Here, an intermediate transfer type image forming apparatus generally called a tandem type will be described as an example.

  An image forming apparatus 100 shown in FIG. 5 includes a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components by an electrophotographic method as an example of an image forming unit including a latent image forming unit and a developing unit. Is provided. Next, the image forming apparatus 100 sequentially transfers (primary transfer) each color component toner image formed by each of the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt (image holding member) 15 as an example of a transfer unit. A primary transfer unit 10 that transfers the superimposed toner image transferred onto the intermediate transfer belt 15 to a sheet that is a recording medium P (recording material (transfer object)). Prepare. Furthermore, the image forming apparatus 100 includes the above-described fixing device 90 that fixes the secondary transferred image on the recording medium P as an example of a fixing unit. Further, the image forming apparatus 100 includes a control unit 40 that controls the operation of each device (each unit).

  As shown in FIG. 5, each of the image forming units 1Y, 1M, 1C, and 1K includes a photosensitive drum 11 that rotates in the direction of arrow A, a charger 12 that charges the photosensitive drum 11, and a photosensitive drum 11. It has a laser exposure device 13 for writing an electrostatic latent image, and a developing device 14 that accommodates each color component toner and visualizes the electrostatic latent image on the photosensitive drum 11 with the toner. Further, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, a drum cleaner 17 that removes residual toner on the photosensitive drum 11, and Have These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. ing.

  The intermediate transfer belt 15 is circulated and driven in the direction of arrow B shown in FIG. As various rolls, a drive roll 31 that drives the intermediate transfer belt 15, a support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that applies a constant tension to the intermediate transfer belt 15 to prevent meandering, and a secondary transfer. A backup roll 25 provided in the section 20 and a cleaning backup roll 34 provided in a cleaning section for scraping the residual toner on the intermediate transfer belt 15 are provided.

  The primary transfer unit 10 includes a primary transfer roll 16 that faces the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The secondary transfer unit 20 is disposed on the back side of the intermediate transfer belt 15 as a secondary transfer roll (transfer member) 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a counter electrode of the secondary transfer roll 22. And a power supply roll 26 that applies a secondary transfer bias to the backup roll 25.

  An intermediate transfer belt cleaner 35 for removing residual toner and paper dust on the intermediate transfer belt 15 is provided on the downstream side of the secondary transfer unit 20. A reference sensor (home position sensor) 42 that generates a reference signal for taking an image forming timing in each of the image forming units 1Y, 1M, 1C, and 1K is disposed upstream of the yellow image forming unit 1Y. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K.

  The recording medium transport system includes a recording medium container 50, a pickup roll 51 that takes out and transports the recording medium P in the recording medium container 50, a transport roll 52 that transports the recording medium P, and a recording medium P. A conveyance chute 53 to be sent to the next transfer unit 20, a conveyance belt 55 for conveying the recording medium P secondarily transferred by the secondary transfer roll 22 to the fixing device 90, and a fixing inlet for guiding the recording medium P to the fixing device 90. And a guide 56.

  A basic image forming process of the image forming apparatus 100 will be described. In the image forming apparatus 100 as shown in FIG. 5, after image processing is performed on image data output from an image reading apparatus (not shown) or the like, the image data is converted into four colors Y, M, C, and K. It is converted into material gradation data and output to the laser exposure unit 13. For example, each of the photosensitive drums that rotates the exposure beam Bm emitted from the semiconductor laser in the direction of arrow A of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. 11 is irradiated. After the surface of each photoconductive drum 11 is charged by the charger 12, the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, and K by each of the image forming units 1Y, 1M, 1C, and 1K.

  Next, the toner image formed on the photosensitive drum 11 is sequentially superimposed on the surface of the intermediate transfer belt 15 in the primary transfer unit 10 to perform primary transfer. The intermediate transfer belt 15 moves in the direction of arrow B and conveys the toner image to the secondary transfer unit 20. The recording medium conveyance system supplies the recording medium P from the recording medium container 50 in accordance with the timing at which the toner image is conveyed to the secondary transfer unit 20. In the secondary transfer unit 20, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred onto the recording medium P sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. Thereafter, the recording medium P on which the toner image has been electrostatically transferred is conveyed to the fixing device 90 by the conveying belt 55, and the fixing device 90 processes the unfixed toner image on the recording medium P with heat and pressure and puts it on the recording medium P. To settle. The recording medium P on which the fixed image has been formed is conveyed to a paper discharge placement unit provided in the discharge unit of the image forming apparatus.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example. The evaluations described in the following production examples, examples and comparative examples were carried out by the following methods.

[Example 1]
A metal shaft adjusted to the core diameter of the core 911 shown in FIG. 1 is attached to a cylindrical mold, and liquid silicone rubber (manufactured by Toray Dow Corning Co., Ltd.) is used as a filler, “Matsumoto Microsphere (registered trademark)”. "FN-80SDE" of 30 parts by mass with respect to 100 parts by mass of liquid silicone rubber to prepare an elastic material. Next, the elastic material is injected between the circular mold and the metal shaft, and the cylindrical mold in which the elastic material is injected is rotated slowly at 5 rpm at 80 ° C. for 5 minutes, and then at 100 ° C. at 50 rpm. Rotate while heating for 15 minutes. Next, the cured elastic cylinder made of silicone rubber is taken out from the cylindrical mold, and the hollow elastic cylinder is fired at 200 ° C. for 2 hours to volatilize the resin filler in the elastic cylinder. Next, the core 911 to which the primer is applied is attached to the hollow portion of the elastic cylinder, and then bonded and fired. Further, the primer is applied to the surface of the obtained elastic cylinder with the core, and another cylindrical mold A heat-resistant resin coating or a heat-resistant rubber coating serving as a release layer is covered inside, and the elastic cylinder is inserted in a vacuumed state, and then returned to normal pressure to form a pressure roll precursor. Then, the pressure roll precursor is taken out from the cylindrical mold, and the elastic layer made of the elastic cylindrical body and the release layer are bonded and fired in an oven so that the major axis A of the oblong hole 914 shown in FIG. A pressure roll with a compression rate of 30%, in which the short diameter B of the flat spherical holes 914 was 20 μm, was produced.

[Example 2]
As the filler, “Matsumoto Microsphere (registered trademark)” “FN-80SDE” is used, and the elastic material is injected between a circular mold and a metal shaft, and the cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 5 minutes at 5 rpm and then rotated at 100 ° C. for 15 minutes at 30 rpm. A pressure roll with a compression rate of 20%, in which A is 24 μm and the short diameter B of the oblong holes 914 is 20 μm, was manufactured.

[Example 3]
As the filler, “Matsumoto Microsphere (registered trademark)” “FN-80SDE” is used, and the elastic material is injected between a circular mold and a metal shaft, and the cylindrical mold in which the elastic material is injected, The long diameter of the oblong spherical hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 10 minutes at 5 rpm and then heated at 100 ° C. for 15 minutes at 50 rpm. A pressure roll with a compression rate of 30% was produced, with A being 39 μm and the short diameter B of the oblong holes 914 being 30 μm.

[Example 4]
As the filler, “Matsumoto Microsphere (registered trademark)” “FN-80SDE” is used, and the elastic material is injected between a circular mold and a metal shaft, and the cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 5 minutes at 5 rpm and then rotated at 100 ° C. for 15 minutes at 30 rpm. A pressure roll with a compression rate of 20% was produced, with A being 36 μm and the short diameter B of the oblong holes 914 being 30 μm.

[Example 5]
As a filler, using “FN-80DE” of “Matsumoto Microsphere (registered trademark)”, the elastic material is injected between a circular mold and a metal shaft, and a cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 15 minutes at 5 rpm and then heated at 100 ° C. for 15 minutes at 50 rpm. A pressure roll having a compression rate of 30% was manufactured, in which A was 130 μm, and the short diameter B of the oblong holes 914 was 100 μm.

[Example 6]
As a filler, using “FN-80DE” of “Matsumoto Microsphere (registered trademark)”, the elastic material is injected between a circular mold and a metal shaft, and a cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1, except that it is rotated slowly at 80 ° C. for 15 minutes at 5 rpm and then heated at 30 rpm for 15 minutes at 100 ° C. A pressure roll having a compression rate of 20%, in which A is 120 μm, and the short diameter B of the oblong holes 914 is 100 μm, was manufactured.

[Example 7]
As a filler, using “FN-80DE” of “Matsumoto Microsphere (registered trademark)”, the elastic material is injected between a circular mold and a metal shaft, and a cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 10 minutes at 5 rpm and then heated at 100 ° C. for 15 minutes at 25 rpm. A pressure roll having a compression rate of 10%, in which A was 110 μm, and the short diameter B of the oblong holes 914 was 100 μm, was produced.

[Example 8]
As a filler, using “FN-80DE” of “Matsumoto Microsphere (registered trademark)”, the elastic material is injected between a circular mold and a metal shaft, and a cylindrical mold in which the elastic material is injected, The long diameter of the oblong spherical hole 914 shown in FIG. 2 is the same as in Example 1 except that it is rotated slowly at 80 ° C. for 5 minutes at 5 rpm and then heated at 100 ° C. for 15 minutes at 20 rpm. A pressurizing roll having a compression rate of 5%, in which A is 105 μm, and the short diameter B of the oblong holes 914 is 100 μm, was manufactured.

[Example 9]
As a filler, using “FN-80DE” of “Matsumoto Microsphere (registered trademark)”, the elastic material is injected between a circular mold and a metal shaft, and a cylindrical mold in which the elastic material is injected, The long diameter of the oblong hole 914 shown in FIG. 2 is the same as that of Example 1 except that it is rotated slowly at 80 ° C. for 5 minutes at 5 rpm and then rotated at 100 ° C. for 15 minutes at 50 rpm. A pressure roll with a compression ratio of 31% was produced, in which A was 130 μm, and the short diameter B of the oblong holes 914 was 90 μm.

[Comparative Example 1]
According to Example 1, except that the elastic material is injected between a circular mold and a metal shaft, and the cylindrical mold in which the elastic material is injected is rotated while heating at 60 rpm at 10 rpm for 5 minutes. Thus, a pressure roll having a compression rate of 30% was manufactured. When the pressure roll was cut in the radial direction, no orientation of the major axis of the pores was observed.

[Evaluation method]
The following measurements were performed on the pressure rolls of the examples and comparative examples. The evaluation results are shown in Table 1.

  The pressure rolls of the examples and comparative examples were cut in the radial direction, and the presence or absence of orientation of the long diameter of the oblong holes in the elastic layer was visually confirmed. Further, the hardness of the elastic layer of the pressure rolls of Examples and Comparative Examples was measured using an Asker rubber hardness meter C type (manufactured by Kobunshi Keiki Co., Ltd.), and the strength of the elastic layer of the pressure roll was measured according to JIS. It measured based on K-6251.

  As an application example of the present invention, there is application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

  1Y, 1M, 1C, 1K Image forming unit, 10 Primary transfer unit, 11 Photosensitive drum, 12 Charger, 13 Laser exposure unit, 14 Developer, 15 Intermediate transfer belt, 16 Primary transfer roll, 17 Drum cleaner, 20 2 Next transfer section, 22 Secondary transfer roll, 25 Backup roll, 26 Feed roll, 31 Drive roll, 32 Support roll, 33 Tension roll, 34 Cleaning backup roll, 35 Intermediate transfer belt cleaner, 40 Control section, 43 Image density sensor, 50 Recording Medium Storage Unit, 51 Pickup Roll, 52 Conveying Roll, 53 Conveying Chute, 55 Conveying Belt, 56 Fixing Entrance Guide, 65 Holder, 67 Lubricant Application Member, 68 Sliding Sheet, 70 Peeling Aid Member, 71 Peeling Baffle 72 Baffle holder, 82 Ceramic heater, 90 fixing device, 91 pressure roll, 92 fixing belt, 93a upstream belt guide member, 93b downstream belt guide member, 100 image forming device, 911 core, 912 elastic layer, 913 release layer, 914 hole , 921 Base layer, 922 Release layer.

Claims (6)

At least an elastic layer and a release layer are provided on the core material,
The elastic layer has a plurality of three-dimensional holes in which at least one of the three diameters is different from the others,
A pressure roll in which a major axis of the pores is oriented in a radial direction of the elastic layer. The holes in the elastic layer are oblate,
The pressure roll according to claim 1, wherein a short diameter and a long diameter of the oblong holes are selected according to the compressibility of the elastic layer at the time of pressing.   3. The pressure roll according to claim 2, wherein B / A, which is a ratio of a major axis A to a minor axis B of the oblong holes, is 0.7 or more and 0.9 or less. A pressure roll according to any one of claims 1 to 3,
The unfixed toner image is fixed to the recording medium by sandwiching a recording medium that is disposed in pressure contact with the pressure roll and carries an unfixed toner image in a nip formed between the pressure roll. A fixing member;
A fixing device.   The fixing device according to claim 4, wherein the fixing member is a fixing roll or a belt member provided rotatably. Latent image forming means for forming a latent image on the image carrier;
Developing means for developing the latent image using a developer for developing an electrostatic image;
Transfer means for transferring the developed toner image onto the transfer medium with or without the intermediate transfer member;
Fixing means for fixing a toner image on the transfer target;
An image forming apparatus including
An image forming apparatus comprising the fixing device according to claim 4, wherein the fixing unit is a fixing device.

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